Integration of natural woods and functional nanomaterials is emerging as sustainable nanotechnology. Covalent organic frameworks (COFs), crystalline nanomaterials with pre-designable functional groups and inherent compatibility with wood, hold great promise in wood nanotechnology but remain challenging in fabrication. Here we report the interfacial synthesis of ionic COF composited woods (iCOFWs), in which the wood skeleton stores aqueous phase with ionic amine monomer and undertakes subsequent reaction with aldehyde monomer in the organic phase. The reactive nucleation is confined in the wood substrate by the aqueous-organic interface and generates high-crystalline ionic COFs (iCOFs) throughout the wood via covalent interaction. As a proof of concept, the iCOFW based on TpPa-SO₃H displays ultrahigh lithium conductivity, physicochemical stability, and antimicrobial properties, which demonstrates applicability in an ionotronic device. Besides, this strategy shows scalability for mass production and versatility for different wood species and iCOFs, offering a powerful and sustainable platform for developing COF-based wood nanomaterials.